1. Technical Field
This disclosure relates generally to surgical apparatus for irradiating tissue after treatment and, more particularly, to a treatment catheter insert for use within a treatment catheter and configured to receive a radioactive source wire.
2. Background of Related Art
Because of certain pathological or physiological conditions, it is often necessary to surgically enlarge a lumen of an organ or vessel of the body. This is particularly true, for example, where a vessel has become constricted or stenosed due to a buildup of plaque on the internal walls of the vessel. One method of opening the constriction involves expanding the constricted portion of the vessel with an angioplasty dilatation balloon. While this is an extremely prevalent procedure, occasionally the vessel walls react to the expansion by producing a proliferation of smooth muscle cell growth which causes the vessel to become constricted or restenosed once again.
Recent developments in the angioplasty field have led to the discovery that by irradiating the vascular tissue after the angioplasty procedure the growth of the cells is significantly inhibited. However, the angioplasty catheter typically has a hollow guide wire lumen that generally runs through the center of the catheter and is open at the distal end. When treating for restenosis by using radioactive sources, such as source wires having a radioactive portion, it is necessary to isolate the radioactive source wire from body fluids thus requiring that whatever lumen the radioactive source wire is positioned in have a closed or sealed distal end.
One solution is to remove the open ended angioplasty catheter and replace it with a treatment catheter having a sealed distal end and capable of receipt of a radioactive source wire or ribbon. One exemplary catheter of this type is disclosed in U.S. Pat. No. 5,556,389 to Liprie.
Alternatively, it would be desirable to provide a closed end treatment insert which can be positioned directly within an angioplasty balloon dilatation catheter or other treatment catheter during a procedure and which is capable of receiving a radioactive source wire therein.
There is provided a hollow, tubular treatment catheter insert having a closed distal end for use within a treatment catheter of the type used to perform an angioplasty procedure. The insert is dimensioned and configured to receive and guide a source wire having a radioactive distal portion into a position adjacent a stenotic site within the vessel. The insert generally includes an insert in an internal segment positionable within a lumen of the treatment catheter and an external segment which extends proximally from the proximal end of the internal segment. The internal segment and external segment have first and second bores, respectively, which together form a single bore for receipt of a source wire. Preferably, the internal segment has a maximum outside diameter of approximately 0.018 inches and a minimum internal diameter of approximately 0.015 inches. The preferred outer diameter insures the insert will fit within a conventional angioplasty treatment catheter guide wire lumen while the preferred internal diameter is sized sufficiently for receipt of a preferred radioactive source wire. Preferably, radiopaque markers are formed at the distal end of the insert to aid in positioning the insert within the treatment catheter.
A connector is provided in an area adjacent the proximal end of the internal segment and the distal end of the external segment. The connector is provided to secure the insert to the treatment catheter to insure that the internal segment of the insert does not move longitudinally within the treatment catheter once in position. Further, where the internal segment and external segments of the insert are formed separately, the connector may provide means for connecting the internal segment to the external segment.
Additionally, a second connector may be provided at the proximal end of the external segment for connection to an afterloader device. In this manner, the radioactive source wire may be safely stored within the afterloader device and thereafter driven out of the afterloader device to a position within the distal end of the internal segment.
There is also provided a system for performing an angioplasty procedure which includes an angioplasty treatment catheter, a hollow tubular insert having a closed distal end for use within the treatment catheter and a radioactive source wire having a radioactive distal tip. The hollow tubular insert is sized to receive the radioactive source wire therein. Additionally, the system may include an afterloader device engageable with a proximal end of the insert and capable of storing and driving the radioactive source wire through the insert.
There is also provided a method of inhibiting restenosis resulting from an angioplasty procedure which generally comprises the steps of inserting a treatment catheter within a vessel of a patient such that a treatment portion of the catheter is positioned within a constricted portion of the vessel and enlarging the constricted portion of the vessel with the treatment portion of the catheter. The method further includes providing a tubular insert having a closed distal end and a proximal end and inserting the tubular insert within a bore of the treatment catheter such that the closed distal end of the tubular insert is positioned adjacent the now enlarged portion of the vessel. The method further includes the step of inserting a source wire having a radioactive distal end within the tubular insert such that the radioactive distal end is positioned adjacent the enlarged portion of the vessel and maintaining the source wire within the tubular insert for a predetermined time sufficient to inhibit the growth of smooth muscle cells.
Preferably, the method additionally includes the steps of securing the insert to the treatment catheter and securing a proximal end of the insert to an afterloader device. Further, the method may also include the steps of using the afterloader device to drive the source wire within the insert and time the treatment period that the radioactive source wire remains within the insert.